Using molecular dynamics simulations, an investigation was made of the effect of vacancies on the dynamic response of single crystal Cu to [100] shock loading, including plasticity and spallation, for an initial vacancy concentration (cv) ranging from 0 to 2%. A fixed impact velocity was adopted, for which plasticity and spall do not occur in the defect-free Cu during compression or tension. It was shown that shear flow strength (compressional or tensile) and spall strength decrease with increasing cv. At the molecular dynamics scales, the vacancy effect becomes pronounced for cv>0.25%, where heterogeneous nucleation of plasticity prevails. Tensile plasticity may play a key role in inducing local heating and the power-law reduction in spall strength. Void nucleation occurs preferentially at highly sheared (plastically deformed) sites.

The Effect of Vacancies on Dynamic Response of Single Crystal Cu to Shock Waves. S.N.Luo, T.C.Germann, D.L.Tonks: Journal of Applied Physics, 2010, 107[5], 056102